A wide variety of tools are commonly used in the oil and gas industry for forming wellbores, in completing drilled wellbores, and in producing hydrocarbons from completed wellbores. Examples of such tools include cutting tools, such as drill bits, mills, and borehole reamers. These downhole tools, and several other types of tools outside the realm of the oil and gas industry, are often formed as metal matrix composites (MMCs) and frequently referred to as “MMC tools.”
An MMC tool is typically manufactured by depositing matrix reinforcement material into a mold and, more particularly, into a mold cavity defined within the mold and designed to form various external and internal features of the MMC tool. Interior surfaces of the mold cavity, for example, may be shaped to form desired external features of the MMC tool, and temporary displacement materials, such as consolidated sand or graphite, may be positioned within interior portions of the mold cavity to form various internal (or external) features of the MMC tool. A metered amount of binder material is then added to the mold cavity and the mold is then placed within a furnace to liquefy the binder material and thereby allow the binder material to infiltrate the reinforcing particles of the matrix reinforcement material.
MMC tools are generally manufactured to be erosion-resistant and exhibit high impact strength. However, depending on the particular materials used, MMC tools can also be brittle and, as a result, stress cracks can occur as a result of thermal stress experienced during manufacturing or operation, or as a result of mechanical stress experienced during operation.